The aims of the proposed research are to determine: (1) if diabetics can discriminate hyper- from hypo- from euglycemia (as some claim), and at what blood glucose levels; (2) if both diabetics and non-diabetics can be taught either to make such discriminations or to make more sensitive discriminations; (3) if plasma catecholamine elevations in response to hypoglycemia are a necessary as well as sufficient condition for a successful discrimination; (4) how often, and at what blood glucose levels, psychological symptoms such as anxiety are reported during hyper- or hypoglycemia; and (5) if psychological symptoms are reported, do subjects learn to recognize them as hypo- and hyperglycemic states. Questionnaires administered to diabetics on an inpatient medical unit specialized for the care and study of diabetics, given at all times of blood glucose determination, will be used to answer #1 and #4 above. A discrimination training procedure, similar to biofeedback, will be used to train diabetics and non-diabetics to recognize hyperglycemia and hypoglycemia, produced with glucose and insulin injections, respectively (#2). The same questionnaires administered during discrimination training, and blood samples drawn during hypoglycemia and analyzed for plasma epinephrine, norepinephrine, and dopamine by high-performance liquid chromatography, will be the methods employed to answer #4 and #3, respectively. This training procedure would allow diabetics to be taught inexpensively both to self-monitor without use of any apparatus their own blood glucose levels, and to differentiate these states from psychological symptoms such as anxiety, a problem for many diabetics. Both of these skills would allow diabetics to care for themselves more successfully.